The present invention relates in general to active bolsters for occupant crash protection in automotive vehicles, and, more specifically, to a trim panel supporting a plurality of separate bladder walls with individual micro gas generators to achieve a non-uniform deployment distance laterally across the trim panel.
An active bolster is a vehicle occupant protection device with a gas-inflatable bladder to absorb impacts and reduce trauma to occupants during a crash. As opposed to deployable air bag cushions that emerge from behind various openings upon inflation, active bolsters use the interior trim surface itself to expand at the beginning of a crash event for absorbing the impact and dissipating energy through the action of an inflation gas. U.S. Pat. No. 8,205,909, issued Jun. 26, 2012, incorporated herein by reference, discloses an active knee bolster integrated into a glove box door that is light weight and visually attractive. U.S. Pat. No. 8,474,868, issued Jul. 2, 2013, also incorporated herein by reference, discloses a typical structure wherein an active bolster includes an outer wall (e.g., trim panel) that faces a vehicle occupant attached to an inner bladder wall along a sealed periphery. One or both of the walls is deformable in order to provide an inflatable bladder. For example, the inner wall may have a pleated (i.e., accordion-like) region that straightens out during inflation. The walls are initially spaced apart by a small amount when in their pre-deployment, non-inflated condition. This allows ingress of the inflation gas in a manner that can achieve an even inflation across the panel.
The inner and outer walls of a typical active bolster are comprised of molded thermoplastics such as polyethylene, polyolefin, or PVC. They are typically injection molded but can also be blow molded. When formed separately, the walls must be hermetically joined around their periphery in order to form the inflatable bladder. The joint must be strong to resist separation as a result of the high pressures during inflation.
In known systems, circumferential pleats have resulted in an expansion trajectory that is perpendicular to the Class A surface in a generally symmetrical manner. This expansion profile has been desirable in most situations where the potential passenger interaction is symmetrical across the face of the bolster. In some situations, however, the Class A surface may be skewed with respect to the impacting passenger. For example, an instrument panel or dashboard in front of a front passenger seat may be curved or swept so that a glove box door is closer to the passenger on the left side than on the right side. A symmetric expansion of an active bolster in the glove box door would result in an uneven impact of the passenger with the bolster.
U.S. Pat. No. 8,448,980, issued May 28, 2013, entitled “Active Bolster with Unsymmetric Pleated Inflation” discloses a bladder having pleats that are radially variable so that unfolding during inflation is biased in a particular direction. Limitations associated with the injection molding or blow molding processes used to manufacture a pleated bladder wall and the limited packaging space available within the vehicle trim structure (e.g., glove box door), the amount of biased expansion obtainable is also limited. For purposes of vehicle styling, it is sometimes desirable to employ significant sweep in the trim surfaces which makes it ever more challenging to achieve a desired deployment orientation for an active bolster.
It would also be desirable to improve the ability to tailor the kinematics of bolster deployment according to expected occupant impact requirements and to reduce the overall costs of active bolsters.